Early closed circuit television (CCTV) surveillance systems provide analog architecture for both live-monitoring using a video matrix switcher and for recording capabilities using video cassette recordings (VCR's). Many analog surveillance systems are being replaced with either a complete digital architecture or modified to a hybrid architecture that enables using the existing analog cameras while gaining recording digital capabilities.
According to a first hybrid approach, analog video streams are received from the analog video cameras by an encoder that converts them to a digital format for delivery over the network. The network, which serves as a virtual switcher, delivers the video stream both for recording in digital format and for live monitoring. A major drawback of such a system is the lack of redundancy capabilities such that in an event of a failure in one of the encoders, video data is neither recorded nor live monitored until the failed encoder is replaced.
According to a second hybrid approach, which is used mainly when analog cabling infrastructure from the cameras to the monitors is already available, the digital system (using encoders) receives video signals for recording while the analog matrix switcher receives video signals directly from the cameras for live monitoring to reduce video latency caused by the network and to improve video quality and reliability. Still, the addition of analog matrices increases the complexity of the system and may cause other reliability problems. It would have been beneficial to decrease the number of elements in the system such that it may reduce the space taken by system and may increase the overall reliability of the system.
It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements.